weathercock
noun
Definitions
A weather vane, sometimes in the form of a cockerel.
One who veers with every change of current opinion; a fickle, inconstant person.
(Chiefly US and Canada) A wind pump style where the top of it behaves like a weather vane, moving with the wind direction, but also with a wheel attached to measure wind speed.
verb
Definitions
(of a boat) To turn upwind because of the difference in water pressure on two sides.
(of an airplane or missile) To veer into the direction of the oncoming (relative) wind.
To act as a weathercock for.